First of all I am using 16x disks. Some brands like memorx work fine. others like maxell(some of them) and tdk will only burn to a max of 8x. However, the TDK are marked as 24x disks !!!
I have a NEC-7800A writer. Anyone have any ideas. Its really bugging me. I use nero to burn stuff and the tdk 16x disks decrease the writer speed from 16 to 8.

smart burn box ??? never heard of that, where is this located?
I've done a mixture of on the fly and off the hard disk.
as for buffer size, when it does recognise disks as 16x, it does them perfectly, so I assume my PC can handle it. XPs inbuilt burning stuff isn't interfering with it, is it?